Surveillance cameras comprise an image capturing lens housed, for example, in a dome-shaped casing and rotatable in a pan direction. Surveillance cameras are adapted to be attached generally to ceilings, and are so designed that the pan axis of the image capturing lens is positioned perpendicular when the camera is attached to the ceiling.
When surveillance cameras of the type described are to be mounted on walls, it is practice to attach a bracket to the wall and mount the camera on the bracket with the pan axis positioned perpendicular.
When to be mounted on the wall, the surveillance camera requires a bracket because the pan axis of the image capturing lens is then positioned at an angle 90 degree different from the pan axis of the camera as attached to the ceiling.
However, the use of the bracket for mounting needs time and labor, entails an increase in the number of parts and results in an impaired appearance since the bracket attached is a projection on the wall.
Accordingly, surveillance cameras are proposed in which the direction of mounting the image capturing lens is shiftable through 90 degree within the casing and which are mountable on the ceiling or on the wall with the pan direction positioned perpendicular.
With the surveillance camera which is shiftable in the direction of installation of the image capturing lens, the angle of rotation (pan angle) in the pan direction must be different when the camera attached to the ceiling and when it is attached to the wall
This is attributable to the following reason. For wide-angle surveillance with the camera as attached to the ceiling, the pan angle needed is nearly 360 degree (for example, 325 degree), whereas if the camera as attached to the wall remains adjusted to wide-angle use, the pan angle will include an area which requires no surveillance, for example, the wall area to which the camera is attached. When the camera is to be attached to walls, therefore, the pan angle must be smaller than is needed for attaching to ceilings, namely, up to 180 degree (e.g., 110 degree).
To change the pan angle after changing the direction of installation of the image capturing lens, it is necessary to alter settings in the control program.
The altered settings will be provided by manipulating switches or by an on-screen display (OSD) function, whereas the pan angle will not be fully satisfactory or will include an unnecessary range beyond the desired pan angle when the operator forgets to provide settings, hence the problem of impaired surveillance performance.